Add span-process-id, span-thread-id.

* tracing-core/span.dylan
  (<span>): Add constant slots for span-process-id, span-thread-id.

* tracing-core/library.dylan
  (module tracing-core): Use threads. Get current-process-id from
   system's operating-system module. Export span-process-id and
   span-thread-id.

* documentation/source/index.rst
  (span-process-id, span-thread-id): Document.

Author: waywardmonkeys

documentation/source/index.rst

@@ -343,6 +343,13 @@ Spans
    :parameter span: An instance of :class:`<span>`.
    :value id: An instance of ``<object>``.
 
+.. generic-function:: span-process-id
+
+   :signature: span-process-id (span) => (process-id)
+
+   :parameter span: An instance of :class:`<span>`.
+   :value process-id: An instance of :drm:`<integer>`.
+
 .. generic-function:: span-start-time
 
    Returns the time that the span was created.
@@ -390,6 +397,13 @@ Spans
 
    * :gf:`span-stop`
 
+.. generic-function:: span-thread-id
+
+   :signature: span-thread-id (span) => (thread-id)
+
+   :parameter span: An instance of :class:`<span>`.
+   :value thread-id: An instance of :drm:`<integer>`.
+
 .. generic-function:: span-trace-id
 
    Return the trace-id for a span.

tracing-core/library.dylan

@@ -14,10 +14,12 @@ define module tracing-core
   use dylan;
   use common-dylan;
   use date, import: { current-timestamp };
+  use operating-system, import: { current-process-id };
   use finalization;
   use plists;
   use simple-random;
   use simple-timers;
+  use threads;
 
   export trace-push,
          trace-add-data,
@@ -31,6 +33,8 @@ define module tracing-core
          span-id,
          span-trace-id,
          span-parent-id,
+         span-process-id,
+         span-thread-id,
          span-description,
          span-start-time,
          span-duration,

tracing-core/span.dylan

@@ -12,6 +12,8 @@ define class <span> (<object>)
     required-init-keyword: trace-id:;
   constant slot span-parent-id :: false-or(<unique-id>) = #f,
     init-keyword: parent-id:;
+  constant slot span-process-id :: <integer> = current-process-id();
+  constant slot span-thread-id :: <integer> = current-thread-id();
   constant slot span-description :: <string>,
     required-init-keyword: description:;
   slot span-annotations :: false-or(<span-annotation-vector>) = #f;